TFT coagulation safeguard

ABSTRACT

A medical TFT instrument of the bipolar design includes at least two electrodes held by electrode carriers movable relative to each other which can be charged with HF current via a respective feed line. A safety switch mechanism arranged in the area of the electrode carriers and interconnected in at least one of the feed lines is additionally provided which, upon transfer of at least one of the electrode carriers into the out-of-function/situation, is brought into an OFF or disconnect position, whereby a HF current supply to the electrode associated with this feed line is disconnected.

RELATED APPLICATIONS

This application is the U.S. National Phase of International ApplicationNo. PCT/EP2013/050403, filed Jan. 10, 2013, which claims the benefit ofpriority of German Application No. DE 10 2012 100 425.0, filed Jan. 19,2012. The contents of International Application No. PCT/EP2013/050403and German Application No. DE 10 2012 100 425.0 are incorporated byreference herein in their entirety.

FIELD

The present invention relates generally to a coagulation safeguard, andmore particularly to an instrument comprising a pivotal or foldable HFelectrode for end-to-end anastomosis with integrated HF powerdisconnection.

BACKGROUND

By end-to-end anastomosis basically an (artificial) anastomosis isunderstood in which two hollow organ sections (e.g. intestine parts) arere-sutured at their opened ends so that a fluid-tight and continuouscourse is formed. It is important in this context that thecircumferential suture results in a completely fluid-tight as well asflexible and tear-resistant connection of the two hollow organ sectionsto be connected which is configured so that an as smooth surface aspossible is formed at the inside of the hollow organ to ensure aninterference-free fluid flow inside the hollow organ.

In the state of the art staple devices in the form of single-useinstruments are known, as disclosed in DE 43 27 233 A1 for example.Consequently, a staple device of this type includes an endoscope shaftat the proximal end portion of which a handpiece for holding the deviceas well as for actuating a staple mechanism is disposed. The staplemechanism consists of a staple magazine distally fixed at the endoscopeshaft approximately in the form of a cylindrical cartridge sleeve inwhich a number of staples circumferentially arranged on a circle aresupported in a spring-biased manner as well as of a staple head orstaple cap which is placed in a mushroom-like manner at the axiallydistal end of the cartridge sleeve and is axially movably guided in thecartridge sleeve by means of a pin fixed thereto. The stapling head isthus adapted to be continuously distanced from the cartridge sleeve inthe axial direction of the staple device, thereby an adjustablecircumferential (annular) axial clearance resulting between the staplinghead and the cartridge sleeve, into which clearance the two ends of thehollow organ to be connected can be clamped. The staple head (or staplecap) as well as the cartridge sleeve are operable via suitabletransmission means inside the endoscope shaft from the handpiece.

The problem of staple devices of this type basically consists inproviding a fluid-tight as well as flexible and tear-resistant suture.For this purpose, in some staple devices two staple rows distanced inthe radial direction of the cartridge sleeve are provided whose staplesoverlap in their engaging areas. Although the degree of tightness andthe tear resistance are improved in this way, radially inwardlyprotruding tissue lobes or folds are necessarily formed, whereby a fluidflow inside the hollow organ can be hindered. For this reason, stapledevices of this type recently have been replaced or supplemented bymedical instruments, preferably having a bipolar electrode structure.

In the present case, too, such instrument includes an endoscope shaftcomprising a proximal handpiece and an endoscope head preferablymechanically as well as electrically connected to the handpiece viaappropriate transmission means inside the endoscope shaft. The endoscopehead substantially consists of a bearing sleeve which is fixedlyattached to the distal end portion of the endoscope shaft in an axiallyconnected manner and at the distal front end of which a firstcircumferential electrode (electrode ring) is mounted, and of arelatively movable electrode shield (electrode cap). For this purpose,the electrode shield includes an axial pin movably guided in the bearingsleeve and coupled/adapted to be coupled to a mechanical transmissionmeans inside the endoscope shaft for operating the same via thehandpiece as well as a circumferential electrode rim arranged at thedistal end of the pin on the same. The electrode rim supports, at theend face thereof facing the bearing sleeve, a second circumferentialelectrode (electrode ring) interacting with the first electrode.

In conformity with the staple devices known per se also in theinstrument of this design, by axially moving the electrode shieldthrough the handle an axial clearance can be set between the electroderim and the bearing sleeve so as to clamp tissue to be connected therebetween and to coagulate (weld or seal) the same by charging theelectrodes with HF current. By this method a flexible and fluid-tighttissue suture is formed without large tissue folds protruding into theinterior of the hollow organ.

However, in instruments of this type the problem exists that at leastthe shield has to pass the joint without lastingly injuring the samewhen the instrument is removed from the hollow organ. There is alwaysthe risk that the HF current supply is inadvertently activated, wherebytissue can possibly be damaged especially in the area of the joint.

SUMMARY

In view of this problem, it is an object of the present invention tofurther develop a generic instrument so that the risk of inadvertenttissue damage by HF action especially when removing the instrument froman organ (preferably hollow organ) is reduced.

This object is achieved by an instrument comprising features that aredescribed herein.

The basic idea of the invention on principle consists in guiding the HFcurrent supply to at least one of the electrodes of a bipolar instrumentaccording to the invention, preferably of the single-use design, via adistal safety switch mechanism (in addition to a main switch in the areaof the handpiece) which safety switch mechanism is arranged (integrated)on/in at least one electrode carrier and which upon transferring theinstrument or the one electrode carrier to the operatingposition/operating situation (situation in which the electrodes are tobe supplied with current) is switched/brought automatically (i.e.automatically by moving the at least one electrode carrier) into the ONposition and upon transferring the electrode carrier to theout-of-operation position/out-of-operation situation (situation in whichthe electrodes are no longer to be supplied with current) isswitched/brought into the OFF position, thereby HF current supply beingnecessarily disconnected (independently of the main switch actuation).By such disconnection of the HF supply at the electrode carrier no moreinadvertent tissue damage can occur, not even when HF activation istriggered by corresponding actuation at the handpiece, for example.

In the concrete case, the instrument is an end-to-end anastomosis HFinstrument comprising an endoscope shaft at the distal end piece ofwhich a substantially annular first electrode (or row of electrodes) isplaced at the end face and comprising an electrode shield or electrodecap mounted at the end side of a (tubular) pin or stick which issupported to be axially movable in the distal end piece (bearing sleeve)of the endoscope shaft. The electrode cap forms sort of a rim-shapedelectrode carrier which on a side facing the end piece supports a secondsubstantially annular electrode (or row of electrodes) interacting withthe first electrode.

Preferably the rim-shaped electrode carrier is centrically supported (ina hinged manner) to be foldable or pivoting on the (tubular) pin. Therim-shaped electrode carrier is pivoted or folded with respect to thepin by means of an actuating rod (needle) supported in/on the pin whichis articulated to the rim-shaped electrode carrier via at least onelever, thereby an axial movement of the actuating rod along the pinbeing transformed into a pivoting or folding movement of the rim-shapedelectrode carrier about the pin. The actuating rod is electricallyconnected to the electrode held by the electrode carrier (row ofelectrodes) and thus constitutes a portion of the HF supply. At the(tubular) pin preferably made of electrically non-conductive material a(single) contact, especially in the form of a sliding contact, is fixed(arranged/formed) which, merely at/from a predetermined axial positionof the actuating rod relative to the pin in which the rim-shapedelectrode carrier is substantially unfolded or swiveled into theoperating position, enters into electric contact with the actuating rodor a contact provided at the latter and thus provides the HF feed line.Accordingly, the HF feed line is disconnected outside the predeterminedaxial position of the actuating rod relative to the pin. The actuatingrod and the contact on the side of the pin thus form the safety switchmechanism according to the invention.

As an alternative, it is also possible, as a matter of course,especially in the case of a not foldable/pivoting electrode cap, toprovide the safety switch mechanism between the endoscope shaft endpiece (bearing sleeve) and the cap pin. In this alternative, HF currentis fed to the cap-side second electrode (row of electrodes) via a feedline that is guided via the endoscope shaft end piece (bearing sleeve)and the cap pin and is closed only at/from a predetermined axialdistance between the electrode cap or electrode carrier and theendoscope shaft end piece. When this predetermined axial distance(range) is exceeded or underrun, the feed line between the pin and theend piece is disconnected.

Summing up, the safety switch mechanism is accordingly coupled to amechanical function of the HF instrument by which at least two HFelectrodes are movable relative to each other so as to be brought intoan operating and/or out-of-operation position.

Another alternative according to the invention provides to detachablyengage, clip or clamp the electrode cap or the rim-shaped electrodecarrier with/to the pin, wherein simultaneously an electric contact withthe electrode on the electrode carrier side is established by thismechanical connection. I.e. the engagement/clipping/clamping at the sametime constitutes also the safety switch mechanism according to theinvention. In this case, the electrode carrier (electrode cap) ispreferably connected to the pin by an electrically insulated orinsulating thread. When the instrument is removed from/pulled out of theorgan, the electrode cap is mechanically stripped off the pin (i.e. offthe engagement); at the same time the electric feed line beingcompletely disconnected at the locking mechanism. The electrode cap isthen so-to-speak dragged via the electrically insulated/insulatingthread. In this way, the electrode cap can be pulled through the suturemade before in a comparatively simple manner, wherein no more HF currentcan be supplied to the electrode arranged thereon.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Hereinafter, the invention will be explained in detail by way ofpreferred embodiments with reference to the accompanying figures.

FIG. 1 illustrates a medical bipolar instrument, preferably of theend-to-end anastomosis design, comprising a number of alternativeaxially movable electrode caps according to the invention;

FIGS. 2a-2d illustrate in detail a first variant of an axially movableelectrode cap according to the invention in the operating andout-of-operation positions; and

FIGS. 3a to 3c illustrate in detail a second variant of an axiallymovable electrode cap according to the invention in the operating andout-of-operation positions.

DETAILED DESCRIPTION

A medical instrument of bipolar design in accordance with one exemplaryembodiment includes at least two electrodes being held by electrodecarriers movable relative to each other which can be charged with HFcurrent via a respective feed line. The medical instrument includes asafety switch mechanism arranged in the area of at least one of theelectrode carriers and interconnected in at least one of the feed lines,which safety switch mechanism is brought into an OFF or disconnectposition only upon transferring the at least one electrode carrier intothe out-of-operation position or situation in which no more interactionof the two electrodes is possible or intended. HF current supply to theelectrode associated with the feed line is thereby disconnected.

The medical instrument can be an end-to-end anastomosis HF instrumentpreferably of single-use design. In addition, the medical instrument caninclude a rigid endoscope shaft at the distal end piece, of which asubstantially annular first electrode is placed at the end face and byan electrode cap including a pin supported to be axially movable in thedistal end piece of the endoscope shaft, wherein the electrode capsupports a second substantially annular electrode interacting with thefirst electrode on a side facing the end piece.

The electrode cap can consist of a rim-shaped electrode carrier which iscentrically supported on the now tubular pin in a hinge-like manner soas to be swiveled into an operating position substantially in parallelto the end face of the distal shaft end piece and into anout-of-function position at an angle of more than 0° with respect to theend face of the distal shaft end piece.

The safety switch mechanism can be mechanically coupled to the electrodecap and especially to the pin thereof such that at a position of therim-shaped electrode carrier outside its operating position the at leastone feed line to the electrode held by the rim-shaped electrode carrieris disconnected.

The rim-shaped electrode carrier can be pivoted relative to the pin bymeans of an actuating rod supported to be axially movable in the pin,the actuating rod being coupled to the rim-shaped electrode carrier viaa joint lever so as to transfer an axial movement of the actuating rodalong the pin into a pivoting movement of the rim-shaped electrodecarrier about the pin.

The actuating rod can be electrically connected to the electrode held bythe electrode carrier and thus constitutes a portion of the HF feedline, wherein at the tubular pin a contact is arranged preferably in theform of a sliding contact which at a predetermined axial position of theactuating rod relative to the pin in which the rim-shaped electrodecarrier is unfolded in the operating position enters into electriccontact with the actuating rod or a contact provided on the latter.

The pin can include at its distal end a snap or lock means forming thesafety switch mechanism which can be mechanically engaged in arim-shaped electrode carrier of the electrode cap so as tosimultaneously establish an electric contact between the pin or a feedline arranged thereon and the electrode on the side of the electrodecap.

The electrode carrier can be connected to the pin via an electricallynon-conductive thread. The at least one electrode carrier can be adaptedto be brought from an operating position clamping tissue to be bonded byaxial movement into an operating position releasing tissue in which theat least one electrode carrier can be transferred into theout-of-operation position by a pivoting or folding movement.

In FIG. 1, a bipolar medical instrument, preferably of the end-to-endanastomosis design, is basically shown. It is pointed out in thiscontext, however, that the basic principle of the present invention asillustrated already in the foregoing is also applicable to medicalinstruments of different configuration, such as pincer-shapedcoagulation instruments or scissors-shaped cutting instruments, in whichat least two electrodes are movable toward each other to enter into anoperating position/operating situation.

The exemplified instrument of the end-to-end anastomosis designaccording to FIG. 1 comprises a preferably rigid endoscope shaft 1 (i.e.more rigid than the organ tissue surrounding the same and thus notadapting to the hollow organ shape) at whose proximal end a handpiece 2is disposed. At the distal end of the endoscope shaft 1 an endoscopehead 4 is provided that substantially consists of a bearing sleeve 6being axially fixed to or integrally formed with the endoscope shaft 1and of an electrode cap (electrode shield) 8 being axially movablyguided in the bearing sleeve 6. At the distal end face of the bearingsleeve 6 a first electrode ring (or circumferential row of electrodes)10 is inserted which is connected via an electric feed line (not shown)passed in the endoscope shaft 1 to a proximal main switch (not showneither) in the area of the handpiece 2.

The electrode cap 8 consists of a rim-shaped electrode holder 12 that iscentrally coupled to a pin 14 such that the rim-shaped electrode holder12 can be either completely disconnected from the pin 14 or can bepivoted or folded vis-à-vis the pin 14, as will be described in detailhereinafter. The pin 14 in turn is inserted or can be inserted to beaxially movable in the distal endoscope bearing sleeve 6. For operatingthe pivoting/folding/disconnecting mechanism and for axially moving thepin 14 within the distal bearing sleeve 6 in the endoscope shaft 1 anumber of push/pull rods or Bowden cables are laid (not shown) which arecoupled distally to the electrode cap 8 and proximally to the handpiece2 and, resp., to predetermined handles of the handpiece 2. Finally asecond electrode ring (or circumferential row of electrodes) 16 which isequally electrically connected/connectable to the main switch via apreferably separate feed line inside the endoscope shaft 1 is mounted onthe rim-shaped electrode holder 12 to the end face thereof facing thebearing sleeve 6.

According to FIG. 1, the handpiece 2 is made of an ergonomically shapedhandle 18 as well as a lever or trigger (first handle) 20movable/pivotal relative hereto via which the integrated main switch(not shown in detail) is operable for supplying HF current to theelectrodes 10, 16. Furthermore, at the handpiece 2 a number of actuatingwheels or buttons (second and third handles) 22, 24 are arranged foractivating the push/pull rods for axial movement of the electrode cap 8relative to the bearing sleeve 6 as well as for operating thepivoting/folding mechanism of the rim-shaped electrode holder 12.

The general constructional design of the instrument according to theinvention for mechanical coupling of the electrode cap to the endoscopeshaft as well as for electric connection of the electrode to the mainswitch are sufficiently known from the state of the art so that in thiscontext a further detailed description can be dispensed with. In thisrespect, hereinafter substantially the individual variants of theelectrode caps according to the invention are described in detail by wayof FIGS. 1 to 3.

As is equally evident from FIG. 1, the instrument according to theinvention in the present case can be equipped with differentlyconfigured electrode caps 8 in the form of the end-to-end anastomosisinstrument. Basically each electrode cap 8 includes the rim-shapedelectrode holder 12 already mentioned before as well as the pin 14extending normal hereto which is adapted to be inserted into the bearingsleeve 6 and to be coupled to an actuating means at least for axialdisplacement of the electrode cap 8. Depending on the design variant,the electrode holder 12 is pivoted (in a hinge-like manner) relative tothe pin 14 or the electrode holder 12 is divided into several parts,each part being adapted to be folded relative to the pin 14.Alternatively, the pin 14 can be formed to include at its distal endportion an engaging or plug-in mechanism by which the rim-shapedelectrode holder 12 can be locked by engagement. Said engaging/plug-inmechanism is configured so that the release direction thereof issubstantially axially aligned with respect to the endoscope shaft 1 andthe releasing force thereof required for disengagement is dimensioned oradjustable so that, when the instrument is removed from the holloworgan, the rim-shaped electrode holder 12 is stripped off the pin 14and/or off the engaging/plug-in mechanism.

FIGS. 2a to 2d illustrate an electrode cap 8 of the present inventionaccording to a first preferred embodiment in an operating and anout-of-operation position/situation.

In FIG. 2a the electrode cap 8 is shown in partial longitudinal sectionas well as in operating position. Accordingly, the pin 14 consists of atube made of preferably non-conductive or electrically insulatingmaterial at the distal end of which the rim-shaped electrode holder 12is centrically hinged so that it can pivot/tilt with respect to thetubular pin 14, as illustrated in FIGS. 2b and 2c . At a proximal endportion of the tubular pin 14 an outer contact ring 26 made ofelectrically conductive material is fixed which preferably protrudesinto portion of the interior of the tube 14. In the tube 14 an actuatingrod or a needle 28 is provided in an axially movable fashion which atthe distal end protrudes from the tube 14 and at the protruding distalend of which a joint lever 30 is hinged which, in turn, is articulatedto the rim-shaped electrode carrier 12 on the rim side (cf. especiallyFIG. 2c ). When, consequently, the operating rod 28 is axially displacedin the tube 14, this movement is transmitted to the electrode carrier12, the latter tilting relative to the tube 14.

The actuating rod 28 is made of electrically conductive material (orincludes an electric line) and is electrically connected to theelectrode ring (circumferential row of electrodes) 16 on the electrodeholder 12. The actuating rod 28 or the line mounted thereto isconfigured so that at a particular axial position relative to the tube14 in which the electrode carrier 12 substantially adopts its functionalposition (cf. FIGS. 2a and 2d ) it enters into contact with the outercontact ring 26 and thus establishes a contact connection with theelectric line passed within the endoscope shaft 1. Finally the actuatingrod 28 protrudes from the tube 14 also at the proximal end and at itsproximal end forms an engaging portion 32 adapted to be coupled to acorresponding actuating mechanism in the endoscope shaft 1.

When, accordingly, the actuating rod 28 is displaced from the axialposition (corresponding to the operating position) according to FIG. 2aor 2 b, in which the electrode carrier 12 is aligned substantially inparallel to the distal end face of the bearing sleeve 6, to an axialposition (corresponding to the out-of-operation position) according toFIG. 2b or 2 c in which the electrode carrier 12 adopts an angle >0°relative to the distal end face of the bearing sleeve 6, at the sametime the electric contact between the outer contact ring 26 and theactuating rod 28 is (automatically) disconnected so that the cap-sideelectrode 16 can no longer be charged with HF current. Even if at thisposition the main switch at the handpiece/handle 2 is (inadvertently)actuated, the cap-side electrode 16 cannot be activated. In this waydamage of the surrounding tissue can be safely prevented.

It is noted in this context that the pivotal support of the rim-shapedelectrode holder 12 can also be replaced with a folding support, as isschematically indicated in FIG. 1 in a variant shown there. In thiscase, the electrode holder 12 can be divided in two, wherein the twoparts are coupled to each other in a hinge-like manner. Each part isoperatively connected to the actuating rod 28 via a separate joint leverso that upon axial displacement of the actuating rod 28 the two partscan be unfolded/opened up like an umbrella.

It is also basically possible to design the electrode cap 8 without anypivoting or folding mechanism, wherein in this case the rim-shapedelectrode holder 12 is tightly connected to the pin 14 (withoutactuating rod/needle). In such design it is possible to form the pin 14of an electrically conductive material (whereas the electrode carrier 12is non-conductive) and to electrically connect it to the cap-sideelectrode 16. The contact ring 26 then would be inserted in the bearingsleeve 6 so that in a particular axial position of the electrode cap 8relative to the distal end face of the bearing sleeve 6 (correspondingto a particular clearance range) it enters into contact with ordisconnects the contact with the pin 14.

Finally, a further variant for an electrode cap 8 according to theinvention is referred to, as shown in FIGS. 3a to 3 c.

In this alternative embodiment, the cap pin 14 according to FIG. 3c istongue-shaped or wafer-shaped, wherein at its distal end portion it isseparated into two spring-elastic fork arms 34. Each fork arm 34 formsan undercut or a notch constituting a respective engagement that facestoward the spreading direction of the respective fork arm 34. Therim-shaped or cup-shaped electrode holder 12 includes in its centralportion a longitudinal slit 36 provided as engaging slit for thespring-elastic fork arms 34. Moreover, at the electrode holder 12 athread 38 made of electrically non-conductive material is fixed which inturn is fastened to the cap pin 14.

The cap pin 14 is electrically conductive at least in portions, whereinalso an electric line 40 leads from the cap-side electrode 12 to thelongitudinal slit in the electrode carrier (not electricallyconductive), as is especially illustrated in FIG. 3a . In the operatingposition according to FIG. 3a the pin 14 is engaged in the longitudinalslit 36 of the electrode carrier 12 via its two spring-elastic fork arms34 so that the electrode carrier 12 is tightly connected to the pin 14with predefined locking force. At the same time, the pin 14 is inelectric contact with the cap-side electrode 16 via the spring-elasticfork arms 34. The thread 38 is wound between the fork arms 34 in thisstate, as this is especially shown also in FIG. 3 a.

From FIG. 3b in combination with FIG. 1 one can infer that in the lockedstate the electrode carrier 12 is aligned substantially in parallel tothe distal end face of the bearing sleeve 6, whereby between the opposedelectrodes 10, 16 (circumferential rows of electrodes) an axial gap isformed. Via a through hole 42 at the proximal end of the pin 14 theelectrode cap 8 is coupled to an actuating mechanism not shown in detailfor axial displacement of the electrode cap 8 in the bearing sleeve 6 sothat the axial clearance can be set to a particular clearance.

When the instrument is to be removed, i.e. withdrawn, from the holloworgan (not shown), the electrode holder 12 strips off the fork arms 34,as is symbolically shown in FIG. 3c . In this case, also the electriccontact between the pin 14 and the cap-side electrode 16 isinterrupted/disconnected. The electrode holder 12 now is suspended onthe pin 14 only via the electrically non-conductive thread 38 and isthus dragged by the endoscope.

Summing up, a medical instrument of bipolar design is disclosedcomprising at least two electrodes 10, 16 held by electrode carriers 6,12 movable relative to each other which can be charged with HF currentvia a respective feed line. In accordance with the invention, a safetyswitch mechanism arranged in the area of the electrode carriers 6, 12and interconnected in at least one of the feed lines is additionallyprovided which is brought into an OFF or disconnect position when atleast one of the electrode carriers 12 is transferred into theout-of-operation position/situation, thereby HF current supply to theelectrode associated with this feed line being disconnected.

The invention claimed is:
 1. A medical instrument of bipolar designcomprising: a rigid endoscope shaft comprising a distal end piece havingan end face; an electrode cap including a pin supported to be axiallymoveable in the distal end piece of the endoscope shaft; at least twoelectrodes comprising a first electrode and a second electrode, thefirst electrode held by a first electrode carrier, and the secondelectrode held by a second electrode carrier, the second electrodelocated at the electrode cap, and the first electrode located at thedistal end piece; a first feed line for feeding current to the firstelectrode; and a second feed line for feeding current to the secondelectrode, the first electrode carrier and second electrode carrierbeing movable relative to each other to enter into an operating positionin which the first electrode can be charged with HF current via thefirst feed line, and the second electrode can be charged with HF currentvia the second feed line so as to interact with each other; and a safetyswitch mechanism arranged in the area of at least one of the first andsecond electrode carriers and interconnected with at least one of thefirst feed line and the second feed line, the safety switch mechanismbeing mechanically coupled to the electrode cap and to the pin such thatthe feed line to the second electrode, held by the second electrodecarrier of the electrode cap, is disconnected if the safety switchmechanism is brought into an OFF or disconnect position exclusively upontransferring the second electrode carrier of the electrode cap into anout-of-operation position or situation, in which the entering of theoperating position is blocked such that no more interaction between thefirst electrode and second electrode is possible, thereby disconnectingHF current supply to the second electrode associated with the secondfeed line, wherein the pin includes at its distal end a snap or lockmeans forming the safety switch mechanism which can be mechanicallyengaged in the second electrode carrier of the electrode cap so as tosimultaneously establish an electric contact between the pin or a feedline arranged thereon and the second electrode, and wherein the secondelectrode carrier is connected to the pin via an electricallynon-conductive thread.
 2. The medical instrument according to claim 1,wherein the medical instrument is an end-to-end anastomosis HFinstrument of single-use design.
 3. The medical instrument according toclaim 1, wherein the first electrode comprises a substantially annularelectrode placed at the end face, wherein the electrode cap supports thesecond electrode, the second electrode comprising a substantiallyannular electrode interacting with the first electrode on a side facingthe distal end piece.
 4. The medical instrument according to claim 3,wherein the second electrode carrier comprises a rim-shaped electrodecarrier which is centrically supported on the pin in a hinge-like mannerso as to be swiveled into the operating position substantially inparallel to the end face of the distal end piece and into theout-of-operation position or situation at an angle of more than 0° withrespect to the end face of the distal end piece.
 5. The medicalinstrument according to claim 4, wherein the safety switch mechanism ismechanically coupled to the electrode cap and to the pin such that whenthe second electrode carrier is in the out-of-operation position orsituation, the at second feed line to the second electrode isdisconnected.
 6. The medical instrument according to claim 1, whereinthe second electrode carrier is adapted to be brought from a firstposition for clamping tissue to be bonded by axial movement into asecond position for releasing tissue in which the second electrodecarrier can be transferred into the out-of-operation position orsituation by a pivoting or folding movement.